Paul withers withers@bu edu boston university maven psg berkeley ca 2011 10 19 20
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Paul Withers [email protected] Boston University MAVEN PSG, Berkeley CA 2011.10.19-20. Thermospheric Variability MCDP Work. But first… Mariner 9 radio occultation electron density profiles. ~100 found at NSSDC Extend to ~400km Ionopause height (Unlike MGS) Spans immense dust storm

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Paul withers withers@bu edu boston university maven psg berkeley ca 2011 10 19 20

Paul Withers

[email protected]

Boston University

MAVEN PSG, Berkeley CA

2011.10.19-20

Thermospheric VariabilityMCDP Work


But first mariner 9 radio occultation electron density profiles
But first… Mariner 9 radio occultation electron density profiles

~100 found at

NSSDC

Extend to ~400km

Ionopause height

(Unlike MGS)

Spans immense

dust storm

Better

geographical and

SZA coverage

than MGS

Anyone want digital copies of these ~100 profiles?


What s the weather like at 150 km
What's the weather profileslike at 150 km?

  • Climate = What you expect (predictions from models)

  • Weather = What you get (less predictable from numerical models)

  • Operations need predictions of both

  • I'm working on some data products associated with empirical measurements of thermospheric variability


Aerobraking accelerometers
Aerobraking accelerometers profiles

  • MGS, ODY, MRO sampled range of seasons, locations, times of day, solar cycle, etc

  • Density profiles, as well as density scale heights

  • Pressure proportional to density x scale height

These four profiles should be identical


Mgs rs ionospheric data
MGS RS ionospheric data profiles

  • 5600 profiles of electron density vs altitude

  • Altitude of peak occurs at predictable pressure level

  • Width of peak indicates neutral temperature

Longitude


Task 1 intrinsic variability
Task 1 (Intrinsic variability) profiles

  • Variability at same Ls, latitude, longitude, LST, altitude (everything but day-to-day)

  • Occurs for aerobraking when period x N = sol

Numbers are standard deviation of selected density measurements relative to mean


Task 1 accelerometer results
Task 1 – Accelerometer results profiles

  • MGS, ODY, MRO

  • Inbound and outbound

  • Dayside and nightside

  • 100 km to 160 km in 10 km intervals

  • Density, density scale height, pressure(-ish)


MRO Outbound 130 km profiles

Nightside Density

Numbers are standard deviation of selected density measurements relative to mean


MRO Outbound 130 km profiles

Nightside Scale Height


MRO Outbound 130 km profiles

Nightside Pressure


Task 1 radio science results
Task 1 – Radio science results profiles

  • MGS

  • Mars Years 24, 25, 26, and 27

  • Variations in peak altitude and fitted scale height

  • Also peak altitude changes normalized by scale height (can be used to get sense of variations in pressure at fixed altitude)


2.5 degree latitude spacing profiles

20 degree longitude spacing

1 hour LST spacing

15 degree Ls spacing

Need 7 points in a 4-D box to define a cluster




Standard deviation of: profiles

Difference between main peak altitude and

a cluster’s main peak altitude, divided by the

average scale height for that cluster

Typical values are 0.2


Task 2 variations with longitude
Task 2 (Variations with longitude) profiles

  • Longitude has a surprisingly large effect on thermospheric densities and temperatures

  • Report standard deviation of density, etc, at fixed Ls, latitude, LST, altitude

  • Identify conditions where thermal tides are strong


Mro outbound nightside density from 90s to 80s
MRO Outbound Nightside profilesDensity from 90S to 80S


MRO Outbound Nightside profilesPressure from 90S to 80S


Task 2 radio science results
Task 2 – Radio science results profiles

  • Similar sort of approach, using variations in peak altitude and fitted scale height

  • Select Mars Year (e.g. 27) and latitude range (e.g. 60N to 70N)

  • Find that selected subset of data forms groups with narrow range in Ls (~15-30 deg) and LST (1-2 hrs)

  • Look at variations with longitude for each group


Task 3 response to extreme solar events not yet started
Task 3 (Response to extreme solar events) – profilesnot yet started

  • Solar flares

  • CMEs

  • Responses not well-known, may be small and hard to measure

  • May be large at times

Densities at 150 km increase during period of high solar EUV flux


Task 4 response to dust storms
Task 4 (Response to dust storms) profiles

MGS TES dust opacity

Noachis dust storm during

aerobraking

MGS Accelerometer density at

140 km outbound during dust storm


Where s the dust
Where’s the dust? profiles

Orbit 25, Ls = 203

Orbit 51, Ls = 227

Orbit 53, Ls = 228-ish

Inbound data at 50N

Outbound data at 30N

Storm at 50S



Decay timescale is longer closer to the storm
Decay timescale is longer profilescloser to the storm

Dust opacity itself decays

faster closer to the storm - ?

Decay

timescale

in degrees

of Ls


Next steps on this task
Next steps on this Task profiles

  • ODY aerobraking started in waning phase of a dust storm

  • Some MGS radio occultation data (>60N) likely to encompass dust storm conditions


Conclusions
Conclusions profiles

  • Tasks 1 and 2 (basic statistics of variability) completed, but deliverables are gigantic set of tables/figures without much interpretation

  • Task 4 (dust storm) well underway, results so far are operationally and scientifically interesting

  • Task 3 (extreme solar events) will be started soon


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